System impacts of electric vehicle charging in an evolving market environment

Reductions in greenhouse gas emissions are a strong incentive for the large scale introduction of electric vehicles. Studies that quantify these environmental benefits have to incorporate emissions caused by generating the electricity used to power the vehicles. We show that an approach that uses the average CO₂ intensity of power generation is inaccurate and one needs to consider the generation capacity that is deployed for the extra load of electric vehicles. Moreover, we show the strong sensitivity of the results on different market environment aspects like charging patterns, generation portfolios, the share of wind energy and CO₂ prices. This strong sensitivity implies that it is very hard to accurately predict future emission reductions of electric vehicles.